最簡單的字符串加密C#實現－移位加密

/*
  Filename: encrypt_string.cs
  Author : zhanghua
  Date  : 2005-08-11
  Fuction : input a strig  and encrypt a string
            加密後的字符串的第一個字符是原先字符串的最後一個字符，
            其余的每一個字符是對應的原字符串中的前一個字符的值加
            上3。
            example： welcome -> ezhofrp
        
*/
using System;

class Test
{
 public static void Main()
 {
  string strInput, strOutput;
  
  Console.WriteLine("please input a string to encrypt: \n");
  strInput=Console.ReadLine();

  
  Console.WriteLine(" your input string is : {0}\n", strInput);
   //Encrypt(strInput);
  
  strOutput = Encrypt(strInput);
 
   Console.WriteLine("strOutput is :{0}\n", strOutput);
 }
  
  private static string  Encrypt(string  strInput)
  {
   string strFont,  strEnd;
   string strOutput;
   char[] charFont;
   int i,len, intFont;
   
   len = strInput.Length;
   //Console.WriteLine(" strInput 's length is :{0} \n", len);
   strFont = strInput.Remove(len-1,1);                                 
   strEnd= strInput.Remove(0, len-1);                                 
                                
   //Console.WriteLine(" strFont is : {0} \n" , strFont);                                 
   //Console.WriteLine(" strEnd is : {0} \n" , strEnd);                                 
                                 
     charFont = strFont.ToCharArray();                                 
   for(i=0; i<strFont.Length; i++)                                 
   {                                 
    intFont = (int)charFont[i] + 3;                                 
    //Console.WriteLine(" intFont is : {0} \n", intFont);                                 
                                     
    charFont[i]= Convert.ToChar(intFont);                                   
    //Console.WriteLine("charFont[{0}] is : {1}\n", i, charFont[i]);                                 
   }
     strFont = ""; //let strFont  null
   for (i=0; i<charFont.Length; i++)
   {
      strFont += charFont[i];
    } 
     strOutput=strEnd + strFont;
     return strOutput;
   
  }
}